Karl-Axel Norberg

ADRENERGIC INNERVATION OF THE INTESTINAL WALL STUDIED BY FLUORESCENCE MICROSCOPY.

Abstract A histochemical study of the intestinal adrenergic innervation has shown, that apart from the vasomotor fibres, most adrenergic nerves terminate in the enteric plexuses, where they are arranged around the intramural ganglion cells in structures highly suggestive of synapses. The muscle layers proper, on the other hand, receive very little adrenergic innervation, probably mostly vasomotor fibres. It is suggested that the adrenergic inhibition of intestinal motility is mediated indirectly by an effect on the postganglionic parasympathetic ganglion cells, and that any direct influence on the smooth muscle fibres is of little importance.

Transmitter histochemistry of the sympathetic adrenergic nervous system

Summary The adrenergic transmitter, NA, can now be visualized by a highly specific fluorescence microscopical method. Results of investigations with this method, which have thrown new light on the organization and dynamics of the sympathetic adrenergic nervous system are reviewed in this paper. Quantitative data have been obtained on the concentration and content of NA in the different parts of the neuron, and it has been shown that the transmitter is in all probability stored to the very largest part in granules which are formed in the cell body and rapidly transported down the axons to accumulate in the varicosities of the synaptic terminals. A reserpine-resistant uptake mechanism for CA in adrenergic neurons has been characterized by experiments in vivo and in vitro . This is an energy-dependent active uptake mechanism located at the level of the cell membrane, and it can be blocked by certain drugs, such as cocaine and desmethylimipramine. Evidence has been presented that the terminal part of the adrenergic innervation apparatus in the effector organs is a true ground plexus in the sense of Hillarp 98,99 , the transmitter being released along the entire length of the terminals. The adrenergic innervation has been mapped out in a large part of the organ systems in various mammalian species. The finding of peripherally located adrenergic neurons and especially the adrenergic synapses in autonomic ganglia show that the autonomic nervous system is built both anatomically and functionally in a more complex way than hitherto thought. Furthermore, striking species differences have been found, as regards the occurrence and number of adrenergic nerves in the tissues. These discoveries make it increasingly important to know the accurate innervation pattern before making physiological or pharmacological experiments, or drawing functional conclusions in respect of monoaminergic mechanisms in the tissues.

ADRENERGIC SYNAPTIC TERMINALS AND NERVE CELLS IN BLADDER GANGLIA OF THE CAT.

Abstract A histochemical investigation of the intramural bladder ganglia of the cat, using a method specific for the adrenergic transmitter, has shown that the ganglia are composed of both adrenergic and non-adrenergic, probably cholinergic, nerve cells. Like certain other autonomic ganglia, the bladder ganglin contain typical adrenergic nerve terminals which form synaptic structures around the non-adrenergic ganglion cells. These systems of synaptic terminals constitute a new mechanism for adrenergic influence on ganglionic transmission.

Evidence for adrenergic nerve terminals and synapses in sympathetic ganglia

Abstract Histochemical evidence has been presented that a monoamine, probably norepinephrine, is located in nerve terminals in sympathetic ganglia of the cat. These terminals were found between and around the ganglion cells, forming structures highly suggestive of synapses. They are probably adrenergic synaptic nerve terminals.

The Blood Flow in Experimental Skin Flaps in Rats Studied by Means of the 133Xenon Clearance Method

The blood flow in skin flaps in rats was studied by 133Xe. Clearance values for two or three parts of the flaps were expressed in per cent of control values for the nonoperated side. Standard-sized skin flaps of different types—double-pedicled, single-pedicled and step-wise formed—were used, and the circulatory variations were studied during the healing period. The blood flow in one of the bases of a double-pedicled flap appeared enhanced during the first postoperative week—possibly owing to a loss of the sympathetic tone due to denervation of the vessels. By cutting the base of a single-pedicled flap at various postoperative intervals the reestablishment of the blood flow over the scar was demonstrated. This was concluded to be the main factor causing postoperative recovery of blood flow. The increase in flow appeared more rapid if the base was divided at an early stage. This observation supports the view that hypoxia stimulates revascularization. A step-wise formation of the flap did not lead to a bette...

Monoamine oxidase activity in rat sciatic nerves after constriction

Abstract The activity of monoamine oxidase (MAO) above and below a ligature of rat sciatic nerve has been studied with biochemical and histochemical methods. In the proximal part of the nerve an increase of enzyme activity to a level of 240% of normal was observed after seven days. At three weeks the values were almost in the normal range. In animals which gad undergone lumbar sympathectomy beforehand, the increase in MAO activity after seven days was significantly lower than in normal animals. After two weeks the sympathectomized group reached a peak activity of 215%, and was normal at three weeks. It is suggested that the earlier accummulation of MAO activity observed in normal nerves at seven days is due to a small but relatively fast-moving MAO pool (probably the mitochondria) within the adrenergic axons. In the distal part there was a decrease in enzyme activity after two or three weeks both normally and after lumbar sympathectomy. Thus, the behaviour of the MAO activity is quite different from that of noradrenaline, dopamine-β-hydroxylase activity and dihydroxyphenylalanine-decarboxylase activity after nerve ligation.

Improvement of blood circulation in experimental skin flaps by phentolamine

Abstract Blood flow through skin flaps in the rat was studied by the 133 Xe-clearance method. In the apex of the flap the flow increased from 18 per cent of the control on the 1st postoperative day to 26 on the 3rd day. Phentolamine caused a dramatic improvement from 28 on the 1st to 69 per cent on the 3rd day. It is suggested that phentolamine protects the smooth muscle cells of the blood vessels, supersensitive due to denervation, from circulating catecholamines. This opens a possibility for preventing flap necrosis.

Effects of Noradrenaline and Felypressin on Cutaneous Local Blood Flow After Sympathetic Denervation: A Study on Rats

The effect of two vasoconstrictors, nor-adrenaline and felypressin (Octapressin®, Sandoz), on the elimination rate of a radioactive indicator 133Xe was studied in rat skin where two areas, the scalp and the back, were compared. After denervation of the scalp skin by means of bilateral excision of the cervical ganglia the sensitivity to noradrenaline was increased, whereas no change in sensitivity to felypressin was shown. The alpha-receptor blocking drug, phentolamine (Regitine®, Ciba), could partly counteract the catecholamine effect, but did not influence the effect of felypressin. This indicates different sites of action for the two vasoconstrictors. It also indicates that felypressin is to prefer as a vasoconstrictor adjunct in denervated tissues.

LACK OF ADRENERGIC NERVES IN THE CIRCULAR SMOOTH MUSCLES OF DUCTUS ARTERIOSUS PERSISTENS

Persistent ductus arteriosus obtained from children at operation were studied by means of a fluorescence microscopical technique, specific for catecholamine containing structures. Adrenergic nerves were found in the peripheral parts of the vessel but were lacking or very sparse in the medial, circular musculature. In this respect the persistent ductus arteriosus differs from the normal ductus, where the medial muscle layer is richly supplied with adrenergic nerves. The results further indicate the necessity of an adrenergic mechanism for the normal closure of the vessel and constitute a new aetiological explanation for the persistence of ductus arteriosus.